This invention relates to an apparatus and a method for associatively retrieving videos and searching an arbitrary video.
Construction of data bases directed to video information such as motion pictures and videos, which have not been handled in the past, has been vigorously made in recent years with a higher operation speed and a greater capacity of computers. With such a technical background, practical utilization of retrieving technology of efficiently selecting a desired scene from among large quantities of videos so built up is now under way. An ordinary retrieving method for such a purpose in the field of the video data base is the one by which a user designates a characterizing feature of a desired scene or its keyword and a computer searches the scene having a coincident keyword. However, it is extremely difficult, not only for inexperienced users but also skilled users in retrieval, to precisely designate the characterizing feature of a given scene, and a desired retrieving result cannot be obtained in most cases.
Books as classical information have a table of contents and an index as auxiliary information for retrieval. The table of contents is information in which keywords symbolizing portions of texts are listed in the sequence of progress in the texts. The index is information which lists important keywords in the texts in the order which is easy to find out, such as in the order of alphabet. The greatest feature common to them is that such keywords are collectively illustrated as a list. They always exist at the beginning and the end of the book, and require no trouble for searching them. A reader can find out one paragraph in the text by looking up the table of contents and the index without considering the keyword himself. The reader can also grasp the outline of the text by referring to the table of contents and can judge within a short time whether or not the book is worth reading.
Retrieval using the table of contents and the index involves the problem that a suitable portion cannot be found out if the number of keywords listed is too large, and, on the other hand, the keywords do not exist from the beginning if the number of keywords is too small. This problem can be solved by conjointly using hypertext or full text retrieval. In other words, the number of items of the table of contents and the index is first limited to a certain extent and is represented to the reader. The reader refers to the text by using temporarily the second best keyword which might be related with an object portion and then searches a keyword having a direct relation with the desired portion in the text. If such a keyword is found out, the object can be accomplished by referring to the desired portion by using the mechanism of the hypertext. This is the technique which is typically used in retrieval of an on-line manual. Though the keywords must be registered in advance in the hypertext, the same procedure can be executed for unregistered keywords when full text retrieval is adopted. In this way, the range of utilization of the table of contents and the index can be expanded depending on the mechanism for associatively tracing the keyword and in many cases, the reader can search the desired portion by merely selecting the keywords which appear in front of his eyes (hereinafter referred to as "associated retrieval").
Such a mechanism is believed to be effective for video retrieval also. In the videos, various matters appearing in the video such as persons, materials, etc, can be used in a manner corresponding to the keywords described above. An essential technique for accomplishing associated retrieval using the matter described above, such as a system of looking up associated scenes and information from the matters appearing on a display screen of videos, is described in JP-A-3-52070 entitled "Associated Information Reference System of Animations". According to this system, means for storing a video period in which each matter in a video appear and the position there of and means for combining associated information corresponding to the former are provided, a jump to an associated scene can be easily made and associated information can be easily called out by pointing one point on the screen in which each matter is displayed. Means for saving the trouble of establishing correspondence between each matter and its associated information by using video processing is described in JP-A-5-204990 filed by the inventors of the present invention.
The prior art technologies described above provide primarily means for establishing correspondence between each matter and its associated information but do not sufficiently examine the construction of an entire retrieving system and simple use of the system by the user. They also involve the problem that only that matter for which correspondence to the associated information has been already established can be associatively traced.